Comparison of subcritical CO_2 extraction with conventional methods of extraction to isolate the flower fragrance from Michelia champaca Linn

摘要

The extraction of champa flowers by conventional methods and compared with the subcritical CO_2 extraction. The headspace volatile composition of living flowers and after plucking was determined by solid phase micro extraction on PDMS fiber for comparison. Solvent extraction of fresh flowers of Michelia champaca with pentane yields 1.5±0.05% concrete. The concrete was extracted with subcritical CO_2 and methanol to separate the absolute and the yields are 70% and 80% of the concrete respectively. Hydro-distillation of the fresh flowers in a Clevenger type unit furnished 0.03% of the essential oil. The chemical composition of the concrete, absolute and essential oil were determined by GC and GC/MS. The chemical composition of absolute obtained through CO_2 extraction method is superior in comparison to absolute produced by methanol process. interestingly, the concrete and absolute contain very less amount of sesquiterpene hydrocarbons. The chief components like indole, methyl anthranilate, methyl benzoate, phenyl ethyl alcohol, phenyl acetonitrile are present in higher percentage in the CO_2 extract. The essential oil contains several components responsible for the top note, but quite different from those present in the pentane extract. The essential oil contains more sesquiterpene hydrocarbon components among these β-elemene (19.8%) is a major component. The higher diffusivity of champa fragrance from the fresh flower may be due to the presence of higher amounts of indole and methyl benzoate, which is presented in the headspace analysis of fresh flower.